The present invention relates to a method for automatically selecting a lens unit among plural lens units having different focal lengths and mounted on a photographic printer and the like.
Some of the conventional photographic printers are provided with a plurality lenses with different magnifications. In order to change the size of enlargement (or magnification of enlargement), it is necessary for an operator to manually replace a lens or to select a suitable lens among the plural lenses on a revolving lens turret by pressing a selector button. In this manipulation, the selection of lens and the correction of exposure for the selected lens are left to the operator's judgement. Replacement of lenses in accordance with the change in the size of enlargement involves much trouble in itself. The conventional printers are thus defective in that the printing process does not proceed smoothly.